class_docstr: Abstract Class for registering and storing mappings from domain
  to bijections/transformations
code: def __init__(self):
      # constraint -> constraint -> transformation
      self._storage = {}
      super(domain_map, self).__init__()
  
file_path: mxnet/python/mxnet/gluon/probability/transformation/domain_map.py
imports: from numbers import Number
  from .transformation import ExpTransform, AffineTransform, SigmoidTransform, ComposeTransform
  from ..distributions.constraint import Constraint, Positive, GreaterThan, GreaterThanEq, LessThan, Interval, HalfOpenInterval
label_desc: Use image node_id 1 to create a new domain_map object  with example: obj = domain_map()